Differential-pressure gage.



P. H. HOPKINS.

DIFFERENTIAL PRESSURE GAGE.

APPLICATION FILED JAN.30,1907

Patented 0011.6

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FRANK HOPKINS, OF SOMERVILLE, MASSACHUSETTS, 'ASSIGNOR TO AMERICAN STEAM GAUGE AND VALVE MANUFACTURING COMPANY, OF BOSTON, MASSACHUSETTS, A CORPO- RATION OF NEW JERSEY.

DIFFERENTIAL-PRESSURE GAGE.

Specification of Letters Patent.

Patented Oct. 6, 1908.

Application filedlanuary 30, 1907. Serial No. 354,859.

To all whom it-may concern:

Be it known that I, FRANK II. HOPKINS, ofsomerville, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Diiierential-Pressure Gages, of which the following is a specification.

This invention relates to gages for indicat-- ing differences between two or more pressures, the object being to .provide an im-. proved, simple and efficient device, which, when connected with different sources of supply, will actuate an indicator so as to show the amount by which one pressure eX- ceedsthe other, rather than to show either pressure absolutely.

'. the features'of my invention.

Of the accompanying drawings,Figure 1 represents an elevation of agage embodying Fig. 2 represents a section of the gage.

The same reference characters indicate the same parts in both figures.

' In carrying out my invention, I secure in ,thecasea of the gage a plurality of nipples b and c which. are adapted to be connected with tubes for conducting fluid, and from which extend curved spring tubes of the ordinary Bourdon type. The passages in the ni ples 0 en directly into the interior of the tu es. 1 rom the nipple b the tube d ex-' tends to the right, as seen in Fig. 1, and forms almost one complete convolution of a spiral and is furnished with a coupling e.

terminating at d where the end is closed, Similarly from the nip le 0 extends to the left a corresponding tu e f terminating at f where'it is closed, and having a coupling 9. It will be understood that if pressure is a plied in either nipple, there-will be a ten ency to straighten the tubes, which will tend to move their closed ends away from each other.

Links h and 'l are pivoted to studs j and k on the cou ling members e and g respectivel said inks being joined by a pivot l to whic 1 is connected. a bell-crank lever m mounted upon a stud n. The arm m of the bell-crank extends to the right and is connected by means of a link 0 with a'lever p having a gear se ment 9 meshing with a pinion on the spin is of a hand or indicator r. The hand, gear segment, and lever p are ractically the same as those ordinarily emp oyed in pressure gages operated by a single pres-- sure.

'0 on the dial s.

As before stated, when fluid under pressure is admitted tothe nipples, the ends of the tubes are pulled in opposite directions, thereby ulling oppositely upon. the links h and 't, tending to move them and the bell-crank m in both directions at once. The motion of one tube is resisted by the pressure acting upon the other, and consequently the resultant motion of the bell-crank and indicator r will be that due to the stronger pressure, and

Will be proportional in amount to the excess of such' pressure. If the two pressuresare egual, there will of course beno movement the parts, and the hand will register zero If, however, the tube f contains a ressure which is, say, four pounds greater t an that in the tube d, the hand will be positioned near the figure 4 on the dial, showing simply the amount by which the greater pressure exceeds the less without any regard to what the absolute values of the pressures are.

One of the principal uses to which such a gage is put is in connection with aVenturi water meter in which water is caused to pass through a. tapered contraction in a pipe.

The pipe is tapped at the beginning of the taper, and at the point of greatest contrac-' tion, and the pipes lead from these separate oints 't0 the nlpples b and 0 respectively. y observing the differences between the pressures at these points, the velocity of flow of the water can be calculated, and a gage such as that described eliminates unnecessary labor and chances of inaccuracy in observing the pressure differences. I claim 1. A differential gage comprising a single indicator, .a plurality of pressure actuated flexible tubes each connected with a separate source of pressure, means so connecting said members as to cause the pressure in each member to directly and positively oppose any movement of the other member, and operating means for the indicator controlled by said connecting means, whereby the indicator is actuated proportionally to the movement caused by the stronger pressure. t

2. A differential gage comprising a single indicator, a-plurality of flexible tubes each connected with a separate source of pressure,

means so connectinglsaid devices'as to cause the pressure in eae device to directly and positivelyopposefiny movement oftlge other member, and operating means tor the indi catonattached to and controlled by said connecting means, \rlterel the indicator is actuated proportionally to the movement caused by the stronger pressure.

3. A differential gage comprising a single indicator, a plurality of curved tubular members supported-at one end and each connectmember, and operating i 4. A ditl'erential gage compri ing a single indicator, a plurality of curred spring tubes each hanng closed ends and each connected with a separate source ol pressure, links un1t- 1 links at their point of union and with a separate source of pressure, a link connected at one end to each of the closed ends of said tubes. the opposite ends of said links being united, and a lever connected with said connected with means for actuating the indicator.

(5. A dill'erential gage comprising a single indicator, a plurality of curved spring tubes each having a closed end and each connected with a separate source of pressure, said closed ends being arranged to mow in o )posite direct ions when under pressure, a link connected at one end to each ol the closed ends of said tubes, the opposite ends ol said links being united. and means operatirerr connected with said links for actuating said indicator.

7. A dillerential gage )ltt[)ll. l]lg a single indicator. a pluralitr ol' llexible members rigidly supported at 'tLtt end and lle.\ibl con- 1 nected at the other end. and a lever for actuating the indicator.

in the closed ends .1:" said tubes and so arranged as to cause the pressure in each tube to oppose the movement and links for actuating said indicator proportionin the other tube, a lever operatn'el connected with said ally to the movement caused by the stronger J pressure.

5. A ditl'erential gage comprising a llt {'lt indicator, a pluralit ol' curred spring tubes each havingaclosed end and cat-h conne ted said lerer being connected to the llexible members, the point ol connection being pertmtnentlr maintained with relation to the l'ulcrum of said lever.

In testimony uhereol' l have allixed my signature. in presence of two witnesses.

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